Hippocampal IEDs during paired-associate encoding did not decrease correct cued recall in 15 RAM PAL1 subjects (ds005059, envelope detector, implant labels from FR1)

In a session-0 sample from the RAM Paired Associates Learning task (PAL1), hippocampal interictal epileptiform discharge (IED) detections during the 4-second study-pair display were not associated with a decrease in later correct cued recall. The primary serial-position-stratified estimate included 15 subjects: the mean difference in recall for pairs with versus without an IED was +0.6 percentage points (95% bootstrap CI, -5.4 to +6.6; one-sided sign-flip p = 0.57; 7 of 15 subject differences were negative). The interval does not exclude a decrease of about 5 points, so the result does not rule out a small effect such as the approximately 4-point effect reported for free recall. The unstratified estimate was -1.1 points (p = 0.36); tests with detector thresholds k = 3 and k = 5 also did not show a significant decrease. At k = 3, a secondary, uncorrected control for IEDs in the 0.5 seconds before pair display gave a decrease of 3.1 points (p = 0.019), outside the encoding window. Twenty-six subjects had hippocampal contact labels available and were analyzed; 15 met the primary test's event-count criteria. Labels were taken from another task for the same subject, assuming the implant was the same. The detector used a 10–60 Hz envelope threshold and detections were not visually reviewed. Only session 0 was analyzed. The small sample and possible sharp-wave or artifact detections limit interpretation.

interictal epileptiform discharges · hippocampus · paired-associate learning · cued recall · intracranial EEG · epilepsy · memory · OpenNeuro